The government's announcement last week that Heathrow's third runway would be axed has rather spoiled the competition launched by Greenpeace last year to come up with a design that would thwart the project.

Still, the competition winners were announced this week, and the effort by Alastair Parvin and Lukas Barry took the prize, with their design for a grass-covered fortress that could be a decent redoubt for a 21st-century Unabomber. Their vision of bucolic brawn and Hardy Boys-style fort building wasn't unique: other entries included a series of underground reed tunnels and an adventure park.

The designs will be on display at the Oxo Tower between 2nd and 6th June.